Multi spot optics in medical applications

ABSTRACT

A device is disclosed for generating a therapeutic photochemical effect to a treatment area. This device includes laser generating means ( 10 ) for generating a primary laser beam, multiple beam formation means ( 14 ) for forming at least two secondary laser beams from said primary beam for irradiating said treatment area. The multiple beam formation means ( 14 ) form the secondary beams by constructive and destructive interference. This device is suitable for treatment of conditions such as tendonitis, soft tissue injuries and lymphoedema.

FIELD OF THE INVENTION

This invention relates to therapeutic medical application of laserradiation to the human body.

BACKGROUND OF THE INVENTION

It is known to apply laser radiation to the human body for a number ofdiverse therapeutic and medicative purposes. One example is the use ofrelatively high power lasers to ablate tissue either internal orexternal of the human body such as the application of relatively highpowered lasers for the sculpting of the corneal surface to correctmyopia. Another, important therapeutic application of laser technologyis the use of low power lasers to effect photochemical reactions(non-heating) for the treatment of pain, soft tissue injuries, healingof wounds and furthermore the treatment of lymphoedema.

For this type of low level laser therapy the frequency, power level(continuously on or modulated on/off duty cycle of the radiation at thesame or changing levels) and characteristics of the laser are determinedby the nature of the treatment outcome desired by a clinician. Asrelatively low power lasers are employed, it is typical to apply thelaser radiation by using a hand held device under the control of theclinician or an appropriately trained operator. The lasercharacteristics are programmed or preset and inherent in all laserdevices safety procedures are recommended and complied with.

The treatment area requiring effective laser irradiation is determinedby the required treatment outcome. In many instances, application of thelaser to a number of distinct regions regularly spaced in a treatmentarea is required to deliver an overall therapeutic benefit. The lowpower laser devices employed to generate the photochemical reactiontypically only generate a beam which effectively covers a region in theorder of one cm². Thus the operator must manually reposition the laserto treat each of the distinct regions within a treatment area. Clearlythis method is somewhat haphazard as a clinician must rely on theirjudgment to ensure that the entire treatment area is being uniformlyirradiated both in terms of intensity and duration.

One attempt to address this significant problem is by the use of“scanning” technology whereby a moveable mirror is introduced into theoptical path of the laser emitting device to change the direction of thebeam in a continuous manner thus covering the desired treatment area.This approach has a number of disadvantages. Firstly, this type of“scanning” probe is a more complex device involving moving parts and asa consequence is not suitable to be hand held. Secondly, in manyphotochemical effect type applications, it is advantageous to treat adistinct region for a predetermined amount of time before moving to thenext region in the treatment area. As a scanning probe continuouslytraverses the treatment area, no distinct region within the treatmentarea will receive radiation for a significant block of time.

To address this disadvantage “cluster” type probe have been developed.These devices include multiple laser diodes enclosed in a singleinstrument head thereby using separate laser devices to simultaneouslyirradiate the individual distinct regions within a treatment area.However, this type of device is bulky and the inherent complexity ofpowering multiple laser emitting devices at the level required fortreatment makes these devices both expensive and difficult to maintain.

Therefore, it is an aim of the invention disclosed herein to provide analternative to the above-described methods of laser radiationapplication which effect a therapeutic photochemical reaction byproviding a device heretofore unknown to the inventor.

SUMMARY OF THE INVENTION

In a first aspect the present invention accordingly provides a devicefor generating a therapeutic photochemical effect to a treatment area,said device including:

-   -   laser generating means for generating a primary laser beam;    -   multiple beam formation means for forming at least two secondary        laser beams from said primary beam for irradiating said        treatment area;    -   wherein multiple beam formation means form said secondary beams        by constructive and destructive interference.

Preferably the secondary beams are formed having predetermined spacingbetween said beams.

Preferably the secondary beams are formed having predeterminedindividual intensities.

Preferably the secondary beams are formed having predeterminedindividual spot sizes and distributions.

Preferably the multiple beam formation means includes a diffractiveelement.

Optionally the multiple beam formation means includes a holographicelement.

Preferably the device further includes positioning means for positioningsaid device at a predetermined distance and orientation from saidtreatment area.

In a second aspect the present invention accordingly provides a methodfor irradiating a treatment area to generate a therapeutic photochemicaleffect, said method including the steps of:

-   -   forming at least two secondary laser beams from a first primary        beam by constructive and destructive interference;    -   positioning said secondary beams at a predetermined distance and        orientation relative to said treatment area;    -   irradiating said treatment area with said secondary beams for a        predetermined time.

BRIEF DESCRIPTION OF FIGURES

Specific embodiments of the invention will now be described in somefurther detail with reference to and as illustrated in the accompanyingfigures. These embodiments are illustrative, and not meant to berestrictive of the scope of the invention. Suggestions and descriptionsof other embodiments may be included within the scope of the inventionbut they may not be illustrated in the accompanying figures oralternatively features of the invention may be shown in the figures butnot described in the specification.

FIG. 1 depicts a diffractive optical element located at the output of alaser emission device and shows a multi beam output following thediffractive optical element;

FIG. 2 depicts a spot pattern generated by the device of FIG. 1;

FIG. 3 depicts a pictorial representation of an array of spot patternscreated on a tissue using a single beam laser emission device; and

FIG. 4 depicts use of a preferred embodiment of the invention for thetreatment of lymphoedema.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

Although a particular medical application is described herein and aparticular laser emitting device configuration is also described, itshould be understood that these details are illustrative only and notmeant to be limiting in any way upon the application or configuration ofthe invention.

FIG. 1 depicts a pictorial representation of a device according to theinvention having a laser emission device 10 that shows a single beam oflaser radiation 12.

Laser radiation 12 although not depicted in detail, may have a number ofcharacteristics such as a predetermined spot size, power,frequency/wavelength and modulation. In a practical application thesingle beam may be designed to have characteristics suitable for thetreatment of lymphoedema. When treating lymphoedema there existpredetermined laser radiation protocols that, in one example, requiresthat the single spot beam be applied to the appropriate gland site (e.g.armpit) and any associated areas of tissue hardness. Also the singlespot beam may be applied to surgical scars. Such scars may result from asurgical procedure conducted prior to the need to treat the lymphoedema.For example the conduct of a mastectomy often is the precursor forlymphoedema in patients.

In each of these cases, irradiation of a relatively large treatment areais required so clearly the treatment process is a laborious andtime-consuming process for both the clinician and the patient, as thesingle spot beam must be applied to multiple distinct regions within thetreatment area.

It is proposed that by locating a specially designed diffractive opticalelement 14 (seen in pictorial form a distance D1 from the output of thelaser device 10) a multitude of individual laser beams be created.Whilst in this preferred embodiment a diffractive transmission gratingis employed other optical elements which are capable of forming multiplesecondary beams by constructive and destructive interference arecontemplated to be within the scope of the present invention. Each ofthese beams in turn forms a laser radiation spot on or about the area oftissue to be treated, which in one example is the armpit of the patient.In FIG. 1, the treatment area is depicted at being a distance D2 fromthe diffractive optical element 14.

Thus the output of a laser device 10 having a predetermined emittingaperture and divergence 12 passes through a diffractive optical element14 to make the apparent aperture of the device appear much larger. Thedistance D1 of the diffractive optical element from the laser apertureand the predetermined divergence of the laser determines thedistribution of the laser light over the patient.

As is readily apparent, a treatment using the multi-beam laser-emittingdevice in this example consists of a one step process. The time fordelivery of the treatment is clearly much shorter and likely moreaccurate than the prior process.

As will be discussed other optical elements can be included in theapparatus such as focussing optics to make each of the multiple spotshave particular size etc. In experimental apparatus the laser diode usedis highly divergent. If that apparatus were required to deliver 17 laserspot treatments over a given area and time, the apparatus would need tobe held off the tissue of the patient by some distance to keep the spotsize of the laser the same as if it were in contact mode. It is possibleto use some lenses prior to or even after the multi-spot optics proposedin this disclosure.

It is also conceivable to use a higher-powered laser to reduce thetreatment time. In which case it might be useful to also use a deviceknown as a homogeniser to keep the whole apparatus within Class Ilimitations. This is one alternative but there are other applicationswhere Class I limitations are not required or warranted.

The spread and characteristics of the array of beams emitted by thelaser device can be defined and controlled at the time of manufacture ofthe device. In particular a specially designed diffractive opticalelement splits the single laser beam into two or more beams. Those beamsdo not have to be circular when they land on the skin surface but couldbe arranged to be a set of lines or ellipses, or other shapes in anappropriate configuration. The distribution of the power of thebeams/lines can also vary. The above performance criteria of a suitablediffractive optical element can be specified to Rochester Photonics,Limo or Diffractive Optics Corporation who can produce a diffractiveoptical element to order.

In the illustrated embodiment the multiple beams are arranged especiallyto create a predetermined beam configuration and characteristic. Themanufacturing process of the diffractive optical element determines thatthe multiple beams are each of the same power distribution or that theymay have a distribution that ranges from, a graduated radialdistribution to homogenous over its area. It is also possible for themanufactured diffractive optical element to provide multi beam arraysthat have an even spread or that cluster in some predetermined way.

FIG. 2 is an example of the spot pattern generated by a diffractiveoptical element wherein each beam has a graduated power distribution andresultant spots that are evenly spread over a predetermined area.

When using a diffractive optical element it may be necessary to use ahigher laser power at the source 10 to ensure that each of the multiplebeams have the requisite power to effect the desired diagnostic ortherapeutic outcome.

Furthermore, the spacing of the diffractive optical element from thepatient will need to be gauged so as to ensure the desired radiationlevel and area of coverage is achieved on the skin or organ to beirradiated. The means of gauging that distance are many and varied.

Referring to FIG. 4, in one embodiment suitable for the treatment oflymphoedema, the gauge may comprise a plastic or metal frame 18 that hasan abutment surface that is positioned on the treatment area to beirradiated whilst the other end is fixed relative to the optical elementor the structure that positions it from the source laser output.Accordingly, frame 18 is adjustably attached to the treatment device 20which incorporates the laser device 10 and diffractive optical element14. Frame 18 can be disposable for those procedures which require adifferent or new sterile apparatus for each use of the device so as toprevent cross contamination. This may be an issue when some patientswill suffer related or sometimes unrelated skin disorders, such asulcers or non-healing pressure sores.

Clearly, frame 18 can be modified to accommodate application treatmentdifferences where for example the treatment area to be treated variesbetween large and small or is located in an awkward to get to area ofthe body.

In another embodiment the laser output is provided to the diffractiveoptical element via an optical fiber or like functioning laser energyconduit (not shown).

The size and power of the one or more lasers illuminating thediffractive optical element may or may not be the same and as such theone or more of the multiple laser beams being output from it will varyas required

FIG. 3 is used to crudely illustrate the spot pattern that could becreated by a clinician using a single beam laser radiating device and itis illustrative to note the inconsistency of the distribution thatresults in some areas being irradiated twice and other areas missing outcompletely.

Contrast the irradiation result pictorially represented in FIG. 3 withthe radiation result depicted in FIG. 2 showing a uniform distributionof laser beam spot energy. Combine that with the speed with which theradiation is applied by a single application of radiation by a clinicianusing the device according to the present invention and the benefits arereadily apparent. In addition treatment protocols are more readilycomplied with resulting in improved treatment outcomes in comparison tothe use of prior art treatment delivery means and methods.

Indications are that the simultaneous application of laser radiation inthe case of lymphoedema treatment has the same effect, if not amarginally better effect than when a single laser beam emission deviceis used by a trained operator.

It will be appreciated by those skilled in the art that the invention isnot restricted in its use to the particular application described.Neither is the present invention restricted in its preferred embodimentwith regard to the particular elements and/or features described ordepicted herein. It will be appreciated that various modifications canbe made without departing from the principles of the invention.Therefore, the invention should be understood to include all suchmodifications within its scope.

1. A device for generating a therapeutic photochemical effect to atreatment area, said device including: laser generating means forgenerating a primary laser beam; multiple beam formation means forforming at least two secondary laser beams from said primary beam forirradiating said treatment area; wherein multiple beam formation meansform said secondary beams by constructive and destructive interference.2. A device as claimed in claim 1, wherein said secondary beams areformed having predetermined spacing between said beams.
 3. A device asclaimed in claim 1, wherein said secondary beams are formed havingpredetermined individual intensities.
 4. A device as claimed in claim 1,wherein said secondary beams are formed having predetermined individualspot sizes and distributions.
 5. A device as claimed in claim 1, whereinsaid multiple beam formation means includes a diffractive element.
 6. Adevice as claimed in claim 5, wherein said diffractive element is areflection grating.
 7. A device as claimed in claim 5, wherein saiddiffractive element is a transmission grating.
 8. A device as claimed inclaim 1, wherein said multiple beam formation means includes aholographic element.
 9. a device as claimed in claim 1, wherein saidtherapeutic photographic effect is generated for the treatment oflymphoedema.
 10. A device as claimed in claim 1, further including apositioning means for positioning said device as a predetermineddistance and orientation from said treatment area.
 11. A device asclaimed in claim 10, wherein said positioning means includes a frame,said frame adjustably attached to said device and when in use providesan abutment surface relative to said treatment area.
 12. A multiple beamformation element for inclusion in the device claimed in claim
 1. 13. Amethod for irradiating a treatment area to generate a therapeuticphotochemical effect, said method including the steps of: forming atleast two secondary laser beams from a first primary beam byconstructive and destructive interference; positioning said secondarybeams at a predetermined distance and orientation relative to saidtreatment area; irradiating said treatment area with said secondarybeams for a predetermined time.
 14. A method as claimed in claim 13,wherein said therapeutic photochemical effect is generated for thetreatment of lymphoedema. 15-16. (canceled)